This invention relates to joints or couplings, and particularly to a compression coupling such as used to make connections in a diesel truck exhaust system between the engine exhaust pipe and the flexible metal hose exhaust stack.
In many installations of flexible hose, tubing and piping, it is desirable to install a completely sealed clamp-type coupling to join together the ends of the hose, tube or pipe sections, which may be of the same or different diameters. Often this has to resist heat and/or vibration. Such a coupling should be strong, easily installed, and removable if the design is changed. These couplings usually have an annular sleeve extending circumferentially around the end portions of the tubes or pipes. The sleeve is circumferentially extensible so that the diameter of the sleeve can be increased and the coupling loosened when fitting the coupling around the joint. The coupling also usually has clamping means for tightening and compressing the extensible sleeve around the tube or pipe ends once the coupling is in place. The compressive force holds the clamp in place and keeps the ends of the tube or pipe sections together. To permit it to be extensible, the sleeve has an axially extending gap which widens when the coupling is being installed and narrows when the coupling is clamped in place. Once installed, some form of sealant is necessary over the gap to provide a complete circumferential seal around the ends of the hose, tube or pipe sections.
In the past, in low-heat applications, the necessary circumferential seal has been supplied by providing an annular gasket which fits circumferentially around the entire sleeve. An outer sleeve was then usually fitted around the gasket, and this outer sleeve was clamped to hold the gasket tightly against the inner sleeve. The resulting product was often a device of three or more layers which was heavy, expensive and difficult to handle. Additionally, the forces on the circumference of the pipes being handled were uneven and caused the pipes to go out-of-round and develop leaks, which add to the air and noise pollution. For high-heat applications, such as truck exhausts, no gasket system has worked due to the high temperatures and the mass of the gasket.